Method and means for receiving wireless waves



Nov. 3, 1931. s. LOEWE- 1,830,611

METHOD AND MEANS FOR RECEIVING WIRELESS WAVES Filed 'April 27. 1927 mum 9 lllli l l l l INVENTOR SXEGMUND LOEWE ORNEY Patented Nov. 3, 1931 1 FICE- 1 SIEGMUND LOEWE, or BERLIN-iRIEb ENAU; ,eniaiviany, ntimate mo RA IO con;

ronA'rIoN- OF AMERICA, .A CORPORATION OEDELAWARE METHOD AND. nleii rs "iron, anonrvrine w I'REL'Ess WAVES Ap lication filed April 27', 1927, stin ng 136,381; in n Germany February 12, 1924;

' Application filed inGermany February12,

This invention relates to a wireless receiver and more particularly to receivers of d the regeneratively coupled type. 1

In the operation of very sensitive receiver arrangements, it is necessary to use regeneratively coupled thermionic tubes. i Itis therefore, customary to bringthe energy picked do up'by the aerial and fed to a triode to act again upon the grid circuit of the first ampliffier or one of the followingamplifiertubes, in' order to insure repeated amplification by one and the same amplifier set. Now, ar-

315 rangements of this -kindinvolve the disadvantage that, if the permissible back-couenergy is supplied tothe antenna and-is ,borhood of the receiver outfit.

'It is an object of this invention to prevent such radiation.

by thearrangement shown inthedrawing,

. In the figure, a

justed so that oscillations are produced, by

triode 1. V

The grid of the triode other hand, it will become positively charged upon each diminution of the plate currenti in the audion tube 19. The mean direct cur-l rent potential which prevails at the gridlOi therefore changes upon each change of the ever, results in the creation of an oscillation in the platecircuit oftriode 1. Theseoscil- -lations have an amplified energy-compared with the incomingjoscillationsso that they can be rendered perceptible directly by the I aid of a rectifier or else they are fed to additional: amplifier stages. What is essential in the scheme is that the frequency of the oscillations' produced by -the triode l in accordance-with the direct current variations in the plate circuit of the detector tube 19.. maybe chosen at will, forinstance, it may be conpling is but slightly exceeded, oscillation of F1 the device is occasioned, with the result that siderably lower-than the incoming frequency.

In this manner, additional amplifierstages may be effectively employed; Atelephone, for example,i s inserted either in the plate or audion circuitsr The advantage offered by V e the scheme is. thatinoreaction upon the Now, according to the disclosures of the presentrinvention, this drawback is obviated antenna can. be produced'by the oscillations occurring in circuit '3. This is true becausethe'antennacircuit is'tuned to a'diiferent fre quency than that at which the oscillator 1 isioscill'ating and hence the tuned antenna a circuit offers an extremely high impedance regeneratively coupled xqthermionic tube is shown, intentionally ad-.

to any lcurrentsflwhich would' tend to be radiated vby virtueof the generation of oscilwlationsin the" oscillator .1. By making the back-coupling between coils 2 and 3,- Now; incoming energy is fed to the antenna- {l andthencesupplied to the grid circuit of a de-:- tector tube 19, the detecting action being in-: sured'in well-known manner by means of a grid condenser 6 and a leak 7 Inserted in: the plate circuit of the detector tube is a resistance 9 which, for example, may also= be directly connected to the grid 10 of ai oscillator loscillate atfa relatively low frequency; such as 50 kilocycles the possibility of radiation will-be still lessened by virtue of thechoice of such a lowfrequency.

- r'Tlieessential an'd basic feature of themvention iaszshoiwn by way of example by the fembodimentgg'ivenain the drawing is capable .ofaa greatnumberof modified clrcuit arrangetnents, aswillibeseen. It includes the 5 following:- A local oscillator or vwave- 1, on the one hand,-1I will be negatively charged owing to the action. I of the stopper condenser 11, while, on the generator of-v anydesiredfrequency, is placed "circuit of triode 1, say, in series with'the I battery, orin one of the following amplifier energy changed by thermionic relay, that v each 'oliangeiinthe vcurrent of the plate circuit f saidnrel ay resultsinthe production of a -local wave train'; though this does not persistu yIndeed, itlastsonly until the impulse an -oscillation-iinpeding 'action by' locally generated oscillationsfand an oscillation re leasing action bytlie incoming currents.

condenser ll' connected in the grid circuit of itiio de l; The grid 10, as a consequence, has 'such a negative charge that local oscillations are not produced. The plate current of the thermionic tube 19, which flows through the (resistance 9, also sets up a negative potential at the grid 10. However, when thecurchanges, for instance, when the, same diminishes, (and this will always happen upon the arising ofthe audionefiect) ,the voltage fall across resistance 9, and consequently the negative charge of the grid 10, decreases.

-When this happens, local oscillations canbe produced at once," and thesepersist until the i plate current of; 19 again changes. circuit arrangement hereinbefore described is .suited both for "the reception of wireless 1. telegraphy signals as ,wellas for telephony work; a '7 a i It is,.ol: course, possible toprovide between antenna at and tube 1; a plurality of radio fre- 7 wireless quency amplifier'and audion circuit connections instead ofonly'one audion arrangement. 1 As to the rest, it may be mentioned .th'at, so far as potential balance is concerned, the only pointofimportance is thata' stationary state of balance is obtained at'such' a L mean direct current potential that the tube just fails to oscillate constantly, andthat,,-; upon this balance being disturbed, the. originla condition is spontaneously restored. At any rate,every transient, disturbance in the mean grid potential will be followed by the.

- production of oscillations in circuit 3, and

this is the'essential feature of the invention.

The operation of the system as shown in;

the drawing may be explained as follows. At

----the time of zero reception, that is, when no signals are being received there is a certain! constant current flowing in the platecircuit 7:7 of audion tube 19. 'This producesa certain late impedance of voltage drop across the resistance 9 of tube 19.- rid 10 of'tube l is connee ted' to the impedance 9 at a'point such- T that relative to thejfilament of tube 1 it -maintained at a potential which prevents H The,

tial unsuited for oscillation generation l claim is; The means adapted to prevent the arising of constant local oscillations consists of the' 1. 1n a radio reeeiviiig' apparatus adapted for the reception and transiormation of electromagnetic waves into sound, a local oscillator, means connected to theg 'id and filament of said oscillator to preventoscillation', and

means responsive to incoming wavesfor' counteracting said oscillation preventing means allowing said local oscillator to oscillate. l rent through the resistance 79 is subject to 2 In radio, receiving, apparatus an antenna; a detector, nieans lior couplingzsaid the, input circuit oil said oscillator in such .a manner that thenolmal plate current of said detector through said resistance maintains the grid ol'said oscillator at a negative poten 3. EA method of operating a regeneratively coupled receiving circuit without radiation WhlCl'i consists in collecting s gnal energy'of adesired frequency, rectifying said energy,

producing; local 7 oscillations lot a L frequency other than saidsignal frequency, modulating said local oscillations with said" rectified signal energy, suppressing saidfloc'al. oscillaitions duringperiods when signal energy is not'tcollected, and,"'finally'detecting and utilizing saidmo'dulated localoscillations. f

4;Al116tll0df0f reception'which consists in collecting'signal energy oi. a desired frequency, producing local oscillations of a diff fe'rent frequency, rectiying said signal energy, modulating said local oscillations with said rectified signal energy 5 and controlling the production of said localoscillations in such a manner that local oscillations are produced only when signalenergy is col- QQSIEGMUND LOEWE,

oscillation generation in tube 1. This bias is by virtue of condenser 11 maintainednot-i circuit'3 and coupling 2. V

1 withstanding the factfthat there is a feed 'back arrangement for tube 1 namely,.tuned; 

